55 
those experiments that would use biological containment at a lower step, 
it would be allowed in a containment laboratory, provided that the work was 
conducted in a glove box system. So this matrix allows for matching more 
closely the approaches for containment that have been used in the past with 
human pathogens to the particular needs of experimental design in the recom- 
binant DNA area. 
Very quickly I would like to show you that efforts of trying to achieve 
some harmonization — What I have here is indicated: the matrix boxes that 
the four basic levels of primary containment in the United Kingdom would 
fall into; and you can see that they are near this center-line diagonal; and 
you can see that their level 3 is basically the same type of facility, but 
less reliance on primary containment, and this is consistent with one of the 
proposals within our Guidelines. 
If we look at the Canadian system, you can see too that they follow 
very closely within this diagonal, and I think the descriptions that we now 
have provide a basis for more similarity to be observed in various national 
guidelines that are being established. The Canadian system has six levels 
of defined containment, and you can see how they run. 
If we could have the lights, I would like to finish by emphasizing a 
few other minor points that represent changes in the proposed revised Guide- 
1 ines . 
At the PI level, in the 1976 Guidelines, safe microbiological prac- 
tices were encouraged but were not required. However, there was a princi- 
ple in those Guidelines that stated that microbiological safety practices 
should be employed in ail work, and what we have done at the PI level is 
basically change the "shoulds" to "shalls" so that rather than encouraging 
safe microbiological practice, we are requiring it. 
At the P2 level we are also requiring the posting of the universal bio- 
hazards sign on those laboratories when work at the P2 level is conducted, 
and we are also requiring that those symbols be placed on refrigerators and 
freezers that are used for storing these materials when work with them is 
not in active use. 
At the P3 level and the P4 level, we have provided guidance in the area 
of containment of laboratory and experimental animals. Specific statements 
were lacking in the 1976 Guidelines, although the principles were there. We 
have attempted to provide more substance to those principles by defining 
precisely the manner in which experimental animals would be housed. 
At the PA level we have increased the age to 18 as a minimum age for 
allowing people to gain access to a P4 facility, and this change was made 
only because it was felt that the age of 18 was an indication more of a 
legal age than any age that we had specified before. We have also included 
at the P4 level a description of what we call a containment suit area. 
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